The present invention relates generally to agricultural implements, and more specifically to locking structure for a tool-supporting linkage to maintain the tool in a preselected raised position with respect to supporting framework.
Agricultural implements commonly utilize linkage structure, such as a four-bar linkage, to support an earthworking tool or row unit in trailing relation to an implement frame or toolbar and to permit the tool or unit to rock vertically with respect to the toolbar when the implement is in the field-working position. At times it may become necessary to remove one or more of the units or earthworking tools from operation while permitting the others to remain operative in the field-working position. For example, a narrow row soybean planter may have planting units supported on four-bar linkages and spaced to plant fifteen inch rows. When planting corn with the same implement, every other planting unit will be rendered inoperable to provide thirty inch row spacings. During planting of the rows with the wider spacing, it is desirable to remove or raise the unused ground row units to reduce wear and tear on the unused units, to improve soil and trash flow and to reduce machine draft load. To accomplish this, the unused row units can be entirely removed from the toolbar or frame, or various types of structure may be utilized to hold the unused units off the ground. Removing the units entirely is relatively time consuming and cumbersome, and therefore is not a desirable or convenient alternative. Devices such as hydraulic powered rock shafts, winch and cable arrangements and manually installed straps secured with bolts are available but are either very costly or time-consuming to operate.